Final CONTRIBUTING.md editing pass for formatting consistency.

[ash-teach]

Ensure that all formatting is consistent throughout the document. Also reference progress in #21. The following checklist compiles some of the more common issues:

• [ ] Ensure headings are logically ordered (i.e. don't skip heading levels: # is followed by ## is followed by ### etc.)
• [ ] All code blocks are wrapped in triple backticks (i.e. ```)
• [ ] All code blocks use appropriate language annotations for syntax highlighting (i.e. ```javascript)
• [ ] All code in code blocks is properly indented and white space is used appropriately
• [ ] All in-line references to code (i.e. keywords, variable names, short statements or expressions, etc.) are wrapped in single backticks (i.e. `)
• [ ] Markdown formatting is used appropriately and consistently (i.e. ordered and unordered lists, tables, bolding and italics).
• [ ] Whitespace is correctly used in the raw .md code (i.e. a new line between every paragraph (including separating headers from text and lists from text).
• [ ] All spurious HTML tags are removed (i.e. no <br> or similar tags are included)
• [ ] All markdown images include an appropriate alt-text.
• [ ] All links are appropriately formatted as hyperlinks

[alinaghale88]

Hi @ash-teach can you please assign this task to me? Thank you

[tharinduj31]

Hi @ash-teach can you assign to me(@tharinduj31). Thank you